124 CHAPTER 6 Clinical outcomes Patients in the multidisciplinary rehabilitation group showed significantly greater increase in functional capability of the upper extremity (SRQ-DLV: GROUP x TIME interaction F(1,25) = 15.38, p = 0.04 part. η2 = 0.17) and a greater reduction of persistent pain than patients in the usual care group (Δ pain: U = 46.00, Z = -2.07 p= 0.04). Post-hoc testing revealed that, whereas patients in the multidisciplinary rehabilitation group showed a significant increase in functional capability (F(1,15) = 19.87, p < 0.001, part. η2 = 0.57) and a significant decrease in pain (z =-2.59, p = 0.01, r =-0.46) from baseline to follow-up, patients in the usual care group did not (SRQ-DLV: F(1,10) = 1.62, p = 0.23, part. η2 = 0.14; pain: z =-0.42, p = 0.68, r =-0.09) (Figure 4, Table 1). Brain-Symptom-Behavior correlations We did not find any significant correlations between changes in affected limbspecific brain activity (in clusters > 10 voxels), behavioral task performance, or clinical improvement (rs < 0.29, p > 0.14). We did find significant correlations between behavioral task performance with the affected limb and related activity in the parieto-occipital sulcus at baseline, and with persistent pain at both timepoints, similar to our previous findings2 (see Supplementary Materials and Supplementary Figure 2). Confirmation of embodied processes Across time-points and groups, behavioral and cerebral responses confirmed that patients employed embodied processes during the motor-imagery task, consistent with previous work: 24, 58 significantly slower RTs (BIOMECHANICAL COMPLEXITY: F(1, 26) = 47.58, p < 0.001, part. η2 = 0.65, Figure 5) and increased activity in a motor-imagery related brain network for biomechanically complex vs. easy (imagined) movements (Figure 5, Supplementary Table 2), and significantly slower RTs when the posture of the own limb was incongruent versus congruent with the stimulus view (POSTURAL CONGRUENCY: F(1, 26) = 14.46, p =0.001, part. η2 = 0.36) (Figure 5). Discussion Despite the fact that clinical improvement was significantly greater after multidisciplinary rehabilitation than after usual care, we found no significant group differences in changes in task performance or in brain activity from baseline to follow-up (18 weeks later). Across groups, NA patients did show improved task performance and increased activity in visuomotor occipito-parietal brain areas, where activity was decreased compared to healthy participants at baseline,7 specifically for imagined movements with their affected upper extremity. These findings indicate that the abnormal cerebral sensorimotor representations that occur in response to peripheral nerve damage in NA2 can recover towards normality. We hypothesized that multidisciplinary rehabilitation, but not usual care, could modify abnormal cerebral sensorimotor representations of the affected upper extremity, as it targets cerebral motor control, whereas usual care typically does not. Instead, we found significant behavioral and cerebral changes in both groups, occurring along with improvements in clinical outcome after multidisciplinary rehabilitation. There are several possible explanations for this apparent discrepancy between clinical and cerebral group
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